A study on solutions to decrease erosion problems and enhance biodiversity and nature development in the river Spui River Spui in Winter – Source: zoom.nl Report Wageningen University, 2014 Bas Schimmel, Carlette Nieland, Corry Teichmann, Femke Jansen & Larissa Gunst Final version: 6 June 2014 Client Name : Delta Talent, ARK Natuurontwikkeling & World Wildelife Fund Company relation : Elma Duijndam, Bas Roels, Gijs van Zonneveld Phone : 06-20449862 E-mail : [email protected] Contractor Authors : Larissa Gunst, Femke Jansen, Carlette Nieland, Bas Schimmel & Corry Teichmann Department : Climate Studies Contact Person : Carlette Nieland Phone : 0623434304 E-mail : [email protected] Date: 6 June 2014 ii Table of Contents Table of Figures v List of Tables vii Summary viii 1 Introduction 1 1.1 Report outline 1 1.2 The Spui area 2 1.3 Climate Change Impacts 3 2 Methodology 5 2.1 Empirical Framework 5 2.2 Data collection 6 2.2.1 Literature study 6 2.2.2 Interviews 6 2.2.2.2 Definition expert 7 2.2.3 Results of first research stage 7 2.3 Questionnaire 7 2.4 Multi-criteria analysis and sensitivity analysis 9 2.4.1 Criteria 10 2.5 Reliability 12 3 Theoretical background 13 3.1 Importance of biodiversity and natural development 13 3.2 Erosion protection 16 3.2.1 River erosion 16 3.2.2 Protection measures 17 4 Results 20 4.1 Potential erosion protection measures 20 4.1.1 Soft engineering techniques 20 4.1.2 Hard engineering techniques 29 4.1.3 Other techniques 32 4.1.4 Overview (dis-)advantages of potential erosion protection measures 42 4.2 Questionnaire 44 4.2.1 Preferable solutions by stakeholders 44 4.2.2 Arguments provided for solution options 46 4.3 Multi-criteria analysis and sensitivity analysis 51 4.3.1 Standardization/Scoring 51 4.3.2 Weighing 52 4.3.3 Ranking 52 4.3.4 Sensitivity Analysis 54 iii 5 Discussion 55 5.1 Methods 55 5.1.1 Questionnaire 55 5.1.2 Multi-criteria and sensitivity analysis 55 5.2 Results 56 5.2.1 Questionnaire 56 5.2.2 Multi-Criteria and Sensitivity Analysis 58 5.3 General remarks 60 6 Conclusion 62 References 64 Appendix 71 A. Interviews 71 a. Interview Schedule (Dutch) 71 b. Interview and trp Spui – Gerard Litjens - Stroming 72 c. Interview Claus van den Brink – Arcadis 75 d. Interview Marjolein Meerburg & Hans de Bart – Waterschap Hollandse Delta (WSHD) 76 e. Interview Arie Broekhuizen & Ary van Spijk – Rijkswaterstaat 77 f. Interview Jan Kruijshoop – Rijkswaterstaat 79 g. Interview Tom Wilms and Steven te Slaa – Witteveen + Bos 81 B. Questionnaire 83 C. MCA 94 I. Scoring 94 II. Ranking 96 D. Open answers questionnaire (Dutch) 97 Hoe bent u betrokken bij de mogelijke (her)inrichting van het gebied rondom het Spui? 97 Over welke effecten van klimaatverandering heeft u gehoord? 97 Wat zijn naar uw mening de belangrijkste gevolgen van de erosieproblemen? 98 Verbreden van de Rivier: Wat vindt u van deze oplossing? 99 Open Haringvliet: Wat vindt u van deze oplossing? 101 Blokkeren van het Spui: Wat vindt u van deze oplossing? 102 Ground Consolidators: Wat vindt u van deze oplossing? 103 Wilgen matrassen: Wat vindt u van deze oplossing? 104 Wilt u hier verder nog iets over kwijt? 106 Indien werkzaam, voor welk bedrijf werkt u? (niet verplicht) 106 Heeft u nog vragen, op- of aanmerkingen naar aanleiding van dit onderzoek? 107 E. Outcomes of the Multi-Criteria Analysis 108 iv Table of Figures Figure 1: Location of area of interest, including the state of water during the summer drought of 2003. Source: Rijkswaterstaat, 2011, p. 54 ..............................................................................................................2 Figure 2: Riprap at the shores of the Spui. Source: Bas Schimmel, 2014 .....................................................................2 Figure 3: Risk of 100-year flood damage for IPCC in Europe. Source: European Environment Agency, 2008 ..........................................................................................................................................................................2 Figure 4: Climate Scenario's for River Rhine. Source: IPCC, in lecture: Dr. Fulco Ludwig: Disaster Risk Management Introduction (2014). .................................................................................................................3 Figure 5: Question from questionnaire: Are you aware of climate change effects in the Spui area? .................4 Figure 6: MCDA framework. Source: Linkov et al., 2004 ...................................................................................................5 Figure 7: Relation of planning process (rectangle) to multi-criteria decision support framework (bubbles) Source: Males, 2002 .........................................................................................................................5 Figure 8: Example of MCA question in questionnaire ........................................................................................................8 Figure 9: Conservation plan and management types 2014 adjacent to the Spui; Source: Adapted from: Provincie Zuid-Holland, 2011; Natuurbeheerplan, 2011 ..................................................................... 14 Figure 10: Photo current situation Spui. Source: Bas Schimmel.................................................................................. 15 Figure 11: Conceptual model of erosion in Spui................................................................................................................ 19 Figure 12: Brush mattress with live fascine toe protection, profile view (left) and plan view (right). Source: Allen & Fischenich, 2001, page 9 .................................................................................................. 21 Figure 13: Ground Consolidator element and the use of this concept on the riverbanks. Source: Witteveen+Bos, 2014 ....................................................................................................................................... 22 Figure 14: The biodegradable geotextiles are pinned into place. Source: Geo- synthetics, 2009 .................... 25 Figure 15: Vetiver grass roots minimizing erosion risks. Source: Holanda & Da Rocha, 2011, Chapter 5.1 ........................................................................................................................................................................... 26 Figure 16: Willow Mattress. Source: Salix, 2014 ............................................................................................................... 27 Figure 17: Profile of stone riprap Source: N.C. Division of Coastal Management, 2014 ...................................... 29 Figure 18: Vegetated gabions: left side vegetated gabion baskets, right side vegetated gabion mattresses. Source: McCullah & Gray, 2005, p. 31, 36 .......................................................................... 30 Figure 19: Ecological top layer on stone riprap. Source: ArchDaily, 2008 ............................................................... 30 Figure 20: Upper: Location of the Haringvliet sluices and the Spui. Lower: The dam consistest of 17 sluices and only open when the river discharge is rather high. Source: Rijkswaterstaat, 2008 ....................................................................................................................................................................... 31 Figure 21: Dikes near the Spui. Upper illustration for current situation and lower illustration for a possible future construction. Source: Van Winden et al., 2010, p. 22 .............................................. 32 Figure 22: Sedimentation increase by opening the Haringvliet would stop the erosion and increase biodiversity by sandy soils. Source: Braakhekke et al., 2012, p. 22. ................................................. 32 Figure 23: Map of the area with Bernisse and Brielse Meer. Source: Google Maps............................................... 37 Figure 24: Measures of Room for the River (Dutch). Source: Factsheet Ruimte voor de Rivier, 2007........... 38 Figure 25: Map of the Spui with lines indicated which ground would be used with doubling (yellow) and trippeling (red) of the river. Source: Google Maps, own adaptations ..................................... 40 v Figure 26: The Sand engine. Source: Stive et al. (2013)………………………………………………………………………….41 Figure 27: Question in questionnaire: Are you familiar with this solution? ............................................................ 43 Figure 28: Self-ranking of options by stakeholders from questionnaire .................................................................. 44 Figure 29: Self-ranking of options by stakeholders from questionnaire. 1 is high preference, 6 is low preference ............................................................................................................................................................ 45 Figure 30: Screenshot of scoring table in the MCA (BOSDA 3.1). Left: group- and sub criteria; Upper right: top five erosion protection measures in comparison to keeping the current situation; ++ is most positive, 0 menas no impact, -- is most negative ........................................... 51 Figure 31: Pie charts of weighed main criteria (numbers given in %) determined by six different stakeholder groups ........................................................................................................................................... 52 vi List of Tables Table 1: Interviewed experts ......................................................................................................................................................7